2. Prepared by
Muneer Ahmed
Department of Water Resources Engineering
3. Dam is a structure built across a STREAM,
RIVER, or estuary to store water. A
RESERVOIR is created upstream of the dam
to supply water for human consumption,
IRRIGATION, or industrial use.
4. Dam is the central structure in a multipurpose scheme
aiming at the conservation of water resources.
Auxiliary works for a dam include spillways, gates, or
valves to control the discharge of surplus water, an
intake structure and means for permitting boats or
fishes to cross the dam.
5. A spillway is a section of a dam designed
to pass water from the upstream side of
a dam to the downstream side.
Types of spillway include:
primary spillway,
auxiliary spillway,
emergency spillway,
fuse plug spillway etc.
13. Significant considerations when building a dam
include:
permeability of the surrounding rock or soil
•earthquake faults
•landslides and slope stability
•water table
•peak flood flow
•reservoir silting
•environmental impacts on river fisheries, forests
•impacts on human habitations
•compensation for land being flooded as well as
population resettlement
•removal of toxic materials and buildings from the
proposed reservoir area
22. By use dams can be classified as:
1.check dam
2.detention dam
3.diversionary dam
4.dry dam
5.saddle dam
6.storage dam
7.overflow dam
8.wing dam
9.cofferdam
24. Detention dams are constructed to minimize the
impact of flooding and to restrict the flow rate of a
particular channel.
25. A diversionary dam diverts all or a portion of
the flow of a river from its natural course.
26. A dry dam is designed to control flooding. It normally holds
back no water and allows the channel to flow freely, except
during periods of intense flow .
27. Saddle dam under construction
A saddle dam is an auxiliary dam constructed to
confine the reservoir created by a primary dam.
28. Storage dams are built to provide a reliable source of water
for short or long periods of time.
31. A weir is a type of small overflow dam that are often
used within a river channel .
32. A wing dam extends partway into a river and forces water into
a fast-moving center channel which reduces the rate of
sediment accumulation.
33. A cofferdam is a (usually temporary) barrier constructed
to exclude water from an area that is normally submerged.
34. By structure dams can be
classified as:
1. embankment dam
2. timber dam
3. arch dam
4. gravity dam
5. steel dam
6. beaver dam
35. Embankment dams are made from compacted earth,
they rely on their weight to hold back the force of water.
36. The San Luis Dam,California is an embankment dam
37. A Timber crib dam, Michigan
Timber dams were widely used early due to ease and speed of
construction. Rarely built in modern times by humans because
of relatively short lifespan and limited height.
49. Location- on the Karnafuli river at Kaptai in Rangamati
district, 65 km upstream of Chittagong.
Length- 670.56m
Height- 45.7m high
Width- 45.7m (at foundation level)
7.6m(at crest level)
The catchment area of the reservoir- 11,000 sq km
Since it is an earthen dam a 16-gated spillway (each 12.2m
by 11.3m) with discharge capacity of 625,000 cusec has been
constructed on the left side of the main dam.
53. Compared to concrete barrage and regulators rubber dams are cheaper and more flexible
and can be fully deflated during the flood season . Rubber dams can be as long as 100m
and used for irrigation , small-scale hydropower generation and rural water supply.
55. Feature Bakkhali Dam Eidgaon Dam
Length (m) 84 52
Height (m) 3.5 3
Maximum water retention depth (m) 4 3
Maximum overflow discharge (cumec) 256 80
Maximum flood flow (cumec) 1073 600
Length of concrete floor (m) 40 33.5
Protective works (m):
Upstream 9 6
Downstream 13 8
Volume of inflated dam (cu m) 1200 800
Weight of dam bag (ton) 14 7
Filling pump capacity (cu m/hr) 150 100
Filling/emptying time (hr) 8.1 8.1
Total cost (million Tk) 36 18
57. About hoover dam…
Official name- Hoover Dam
Impounds- Colorado River
Locale- Nevada-Arizona United States
Length- 1244 ft (379 m)
Height- 726.4 ft (221 m)
Construction began- 1931
Opening date- 1936
Construction cost- $49 million
